Screw thread rolling apparatus



Aug 20, 1935. C HANDEL 2,011.761

SCREW THREAD ROLLING APPARATUS Filed Aug. 21 1935 s Sheets-Sheet 1 FiledAug. 21, 1933 3 Sheets-Sheet 2 lrurenlror 19351- I c. E. HANDEL2,011,761

SCREW THREAD ROLLING APPARATUS Filed Aug. 21, 1933 s Sheets-Sheet sPatenteJ Aug. 20, 1935 SCREW THREAD ROLLING APPARATUS Charles E. Handel,Winter-set, Iowa, assignor to Munson Manufacturing "Iowa, a corporationof Iowa Company, Winter-set,

Application. August 21, 1933, Serial No. 686,083

The object of 'my invention is to provide an apparatus of simple,durable and inexpensive construction for forming rolled threads uponround metal rods,, and in which the thread rolling is accomplished bymeans of a ,series of cylindrical rollers equally spaced about the .rodto be threaded, and which, when rotated relative to the rod, willprogressively depress small segmental portions of said rod and formscrew thread grooves, and at the same time progressively force smallportions of the metal of said rod to flow outwardly radially of the rodto form a screw thread raised above the normal'diameter of the rod, andwhereby with a ,minimum of applied power a standard thread may be formedon a metal rod, and whereby theflnished rod willhave substantially thesame tensile strength at the screw threaded portion as it has at anunthreaded portion.

A further object is to provide a screw thread isbeing formed upon a rod,its complete side faces will be formed, initially at relatively slightangles and uniformly and progressively increasing to greater anglesuntil a so-called standard thread is formed, which will thereby retainthe full strength of the material.

My invention consists in the construction, ar-

rangementand combination of thevarious parts of the device, whereby theobjectsicontemplated.

are attained, as hereinafter more fully set forth, pointed out in myclaims, and illustrated in the accompanying drawings, which:

Figure 1 shows aside elevation of an ordinary machine lathe having myimproved screw thread rolling apparatus applied thereto, having a rod tobe threaded supported in position to be operated upon. I Figure 2 showsa vertical, transverse, sectional view through my improved rollersupporting head, illustrating the means for moving the rollersinwardly-and outwardly, and for locking the rollers at their inwardlimit of movement.

Figure 3 shows a sectional view on the line 3-3 of Figure 2.

Figure 4 shows an enlarged, detail, side elevation of one of my improvedrollers, and a portion of a rod having a screw thread formed thereon.

Figure 5 shows an endelevation of same with the rod in section andillustrating by dotted lines the depth of the screw threaded grooveformed in the rod, and the height of the screw thread apex raised abovethe normal diameter of the rod, and also illustrating by' dotted linesthe relative positions of the several annular thread rolling ribs uponthe roller. I

Figure 6 shows a detail, longitudinal, sectional view of a portion of acompleted screw threaded rod, and illustrating by dotted lines therelative angularity and shape of the screw thread as it is progressivelyformed by my improved apparatus. Figure 7 shows a sectional view throughthe roller supporting head taken on the line 8-8 of Figure 3.

Figure 8 shows a detail section view on the line 99 of Figure 8; and

. Figure 9 shows an outer side view of the roller supporting head.

'Referring to the accompanying drawings, ,1 [I

apparatus applied thereto with a rod l2 to be 20 threaded extendedthrough said apparatus. My improved roller head is applied to the lathein the same manner in which an ordinary tool supporting head is appliedthereto.

My improved roller supporting head comprises 28 a cylindrical body l3having fixed thereto an end member I. Fixed in position within thecylinder l3 are the roller supporting disks I6, provided with threeradially extended grooves in which are slidingly mounted the rollersupporting plates I1. 30

These plates ll, as wiil be seen in Figure 2, are arranged radially andequidistant, and each plate I1 is provided at its outer end with a lugI8 having one side beveled at I9, and the other side provided with asquare shoulder 20 and springs 2| are provided for each of the plates Hfor normally holding the plates outwardly. Rotatively mounted upon thecircumference of the cylinder I3 is a cylindrical collar 22 havingopenings 23 therein to receive the lugs l8.

Assuming that the lugs l8 are projecting out through the openings 23,then'as the cylindrical collar 22 is moved clockwise, as shown in Figure2, the inclined surfaces IS on the lugs l8 will be engaged by thecylindrical collar 22, and the said plates ll will be forced inwardly tothe position shown in Figure 2, and when the cylindrical collar 22 ismoved in the opposite direction, the plates l1 will be moved outwardlyby the springs For efiecting this adjustment of the plates ll I havepivoted to one of the roller supporting disks IS a lever 24, extendedthrough a slot 25 in the cylindrical collar 22, and so arranged that 5when this lever is moved by the operator, it will move the cylindricalcollar 22 with it, and by this means it is obvious that the rollercarrying plates I1 may be moved inwardly against spring pressure andlocked at their inward limit 01' movement, and may also be released andmoved outwardly bytheir springs when the lever, 24 is moved in theproper direction.

Mounted in each one of the three pairs of rollor supporting plates I! isa thread forming roller. This thread forming roller is formedof a singlepiece of material and is provided with centrally arranged bearings 26 inits ends. These bearings are mounted in the roller supporting plates l1.

Formed upon the periphery of the roller is a series of annular threadrolling ribs, with annular thread rolling depressions between them. Oneof these ribs, which is intended to perform the initial thread rollingprocess, is arranged at the end of the roller which I have referred toherein as the starting end, and this rib, indicated by the numeral 21,is formed with straight flat side faces arranged with relatively slightdegrees of angularity relative to the surface of the cylinder, and thefiat side face of said rib 21 on the side opposite from the starting endof the rollers extends to the bottom' of the thread forming grooveindicated at 28.

The second one of said thread roiling ribs from the starting end of theroller has its apex indicated by the numeral 29, and the next threadgroove between the ribs is indicated by the numeral 30. The apex 29 ofsaid rib projects radially outwardly from the center of the rollerfarther than the apex of the rib 21, and also the bottom of the groove30 extends deeper into the roller than does the bottom of the groove 27,and in addition thereto the sides of said rib are straight from the apex29 to the bottom of the groove 30, and are arranged at a greater degreeof angularity than that of the corresponding side of the first threadrolling rib at the starting end of the roller.

This same arrangement is carried out in the construction of several ofthe remaining thread rolling ribs, each one progressively, from thestarting end to the finishing end of the roller, has its apex projectedfarther outwardly from the center of the roller than the precedingone,'and has its thread forming groove extended deeper into the rollerthan the preceding one, and the sides of the ribs are progressivelyarranged at greater degrees of angularity, and the last rib at thefinishing end has its sides of such angularity as will in operation formwhat is known as a standard thread.

These rollers, preferably three, are mounted in their supporting platesI! with their axes of rotation parallel radially with the axis ofrotation of the roller supporting head, but each of the rollers has itsaxis inclined slightly in a lateral direction relative to the axis ofrotation of the roller head, as clearly shown in Figure 5.

In practice and assuming that it is desired to thread a rod, andassuming that the roller head and rod are supported on a lathe in the.manner illustrated and described with the rod supporting standardcapable of free longitudinal sliding movement, then the roller head isrotated and the rod fed into it until the apex of the starting rib 21engages the rod. When the head has been rotated approximately one-thirdof a revolution, then the apex of the rib 21 on the second roller willenter the groove in the rod formed by said rib on the first roller,because the second roller is spaced slightly in the rear of the first,and this same action will occur with the apex of the rib 21 on the thirdroller, becauseit also is spaced slightly in the rear of the secondroller.

Since the rollers are locked against outward movement, it is obviousthat a rotation of the head must force the annular ribs on the rollersinto the material of the rod, and form a screw thread thereon. The apexof the starting rib 27 is relatively blunt, that is to say, its sidesare arranged on relatively slight angles. However, this rib, due to thestructure and arrangement of the roller, will penetrate the surface ofthe rod being rolled only for a relatively short segmental portion, asillustrated in Figure 5, where the line 3| indicates the line of the ribapex 21, and the line 32 indicates the normal circumference of the rodbeing rolled, and then when the said annular ribs on the rollers, nearthe finishing end of the roller, pass through this same screw thread on,the rod, they will penetrate the rod much deeper and through segmentsof greater length, as shown by the dotted line 33 in Figure 5.

By this arrangement each annular rib on the roller requires about thesame amount of pressure to cause it to perform its part of the threadrolling operation, because those ribs which have their sides at slightangles penetrate the rod to a less depth and through shorter arcs, andthose ribs toward the finishing ends of the rollers which penetrate therod deeper have their sides at greater angles and operate on the rodthrough greater arcs, as shown in Figure 5,- and the latter annular ribshave the threads more or less com-- pletely formed before they engageand clotheir work upon the rod.

One of the important results which I attain by the use of my improvedapparatus is that while the initial part of the thread is being formedupon the rod, a groove in the rod is formed, which is comparativelyshallow, but the sides of the groove are arranged on relatively slightangles, and these sides are straight from the bottom of the groove tothe apex of the next thread. This is illustrated by the dotted lines 34in Figure 6, and when the second thread forming rib 29 is passed throughthe thread on the rod to form a thread, the bottom of the groove isslightly deeper as shown at 35 in Figure 6 and between these grooves 34and 35 the pressure upon the rollers will cause the material of the rodto flow outwardly radially of the rod to a point beyond the normaldiameter of the rod, thus forming a slightly raised thread portion withthe sides between the bottom of the groove and the apex of the thread,and which are smooth and fiat, and which are arranged at greater anglesrelative to the longitudinal axis of the rod, as illustrated by thedotted lines 36 in Figure 6, and then when the finishing rib on theroller is passed through the same thread on the rod, the groove isformed of greater depth into the rod, and the rib is pressed outwardlystill farther beyond the normal diameter of the rod, as illustrated bythe solid lines 31 in Figure 6.

I have found in practice that by thus progressively deepening thegroove, and causing a flow of metal outwardly from the normal diameterof the rod, and that by keeping the sides of the rib substantiallystraight at all times during this rolling operation, the apex of thescrew thread on the rod will not only retain the normal strength of thematerial of the rod, but will be additionally strengthened by thisrolling on the familiar principle of annealing metal by such working.

One of the advantages of my improved apparatus is that a thread maybeformed of any desired length upon a rod.

In Figure 4 of the drawings I have used the dotted line 38 to indicateupon said figure the position of the normal or unthreaded surface of therod being operated upon, and I have used the dotted line 39 to indicatethat the annular thread forming ribs on the roller progressivelypenetrate deeper into the rod during a thread rolling operation, and Ihave used the dotted line 40 to indicate that the apex of the threadbeing formed on the rod projects beyond the normal surface of the rodprogressively greater as the finishing end of the roller completes itsoperation.

In practice I have employed one or more additional annular ribs at thefinishing end of the roller, all of the same diameter and shape, andthese additional annular ribs are useful not for purposes of shaping thethread, but for polishing or smoothing it. I have, however, found inpractice that a satisfactory thread may be rolled upon a rod withrollers having three or four annular thread rolling ribs of graduallyincreasing diameter toward the finishing end of the roller, and withgrooves between them of gradually decreasing diameter toward thefinishing end of the roller.

' In the accompanying claims where I refer to the finishing end portionof the roller, I do not desire to be understood as limiting the claimsto the last annular rib on the roller if there are several such ribs ofthe same size and shape, but

desire to be understood as referring to that portion of the roller atwhich the major operation 01 shaping the screw thread on the rod iscompleted.

I claim as my invention: 1. In a'thread rolling device of the classdescribed, a roller substantially cylindrical in form and having formedon its periphery a series of annular ribs with grooves between them, thediameters of said ribs being progressively increased from the startingtoward the finishing end of the roller, and the diameters of saidgrooves being progressively decreased fromvthe starting toward thefinishing end of the roller.

2. In a thread rolling device of the class described, a rollersubstantially cylindrical in form and having formed on its periphery aseries of annular ribs with grooves between them, the diameters of saidribs being progressively increased from the starting toward thefinishing end of the roller, and the diameters of said grooves beingprogressively decreased from the starting toward the finishing end ofthe roller, and the angularity of the sides of said thread forming ribsand grooveson the roller being progressively greater from the startingend toward the finishing end of the roller.

3. In a thread rolling device of the class described, a rollersubstantially cylindrical in form and having formed on its periphery aseries of annular ribs with grooves between them, the diameters of anumber of said ribs being progressively increased from the startingtoward the finishing end of the roller, and the diameters of a number ofsaid ribs at the finishing end of the roller being substantially thesame, and the diameters of a,number of said grooves at the starting endof the roller being progressively decreased from the starting toward thefinishing end of the roller, and a number of grooves at the finishingend of the roller of substantially the same diameter.

CHARLES E. HANDEL.

